1. Field of the Invention
The invention relates to a branch-off article suitable for sealing a branch-off region of a cable having a plurality of break-out members extending therefrom.
2. Description of the Prior Art
A telecommunications cable generally contains numerous individual information-carrying conductors, generally in the form of wires, which at some point are branched off from the cable, generally in groups, to form smaller cables, and eventually the wires are individually branched out as drop wires. Whenever a branch-off occurs, the branched-off drop wire or group thereof is generally referred to as a break-out member, the member also including a reduced-sized cable created downstream of a branch-off. A region where the branch-off occurs is referred to as a branch-off region.
Various methods and apparatuses have been proposed in the prior art for sealing the branch-off region, especially when the cable is pressurized, so that adverse environmental contaminants cannot enter the branch-off region. Meltsch, et al., U.S. Pat. No. 4,438,294, describes an apparatus for sealing a branch-off region wherein a liner element is received within a shrinkable tube or socket so as to form first and second conduits for accommodating first and second break-out members. A thermoplastic sealing material is utilized to enhance sealing around the break-out members. A disadvantage of this apparatus is it is craft-sensitive to assemble, and is further disadvantageous in that relatively few break-out members can be accommodated.
Thayer, et al., U.S. Pat. No. 4,343,844, describes a break-out member sealing apparatus comprising a recoverable sleeve having an intricate cell-like internal construction which defines a plurality of longitudinally extending passageways therethrough. Subsequent to inserting break-out members through the passageways, the sleeve is recovered forming a seal around the break-out members. Though this apparatus is superior to the one described by Meltsch in that a relatively large number of break-out members can be accommodated, this apparatus has a very intricate internal design and hence requires a relatively large cost to produce, and is further extremely craft-sensitive to install.
An alternative method and apparatus for branching off a plurality of break-out members from a cable is disclosed in Paget, et al., U.S. Pat. No. 4,467,137, assigned to the assignee of the present invention, the disclosure of which is incorporated herein by reference. According to this apparatus, a branch-off article includes a branch-off member which comprises a body portion and a plurality of tubes extending therefrom with the tubes being formed of a dimensionally recoverable material and being provided in an expanded state. The branch-off member is oriented such that tubes are outside an area enclosed by an outer sealing member (e.g., a recoverable sleeve), with ends of the tubes being recovered about individual ones of the break-out members extending from a splice area. Though the apparatus disclosed by Paget et al is quite effective in branching out a plurality of break-out members, if a cable to which the break-out members is connected is pressurized, the pressurization within individual ones of the break-out members tends to resist a seal formed between the break-out members and the recovered tubes.
Examples of other known branch-off articles are found in U.S. Pat. Nos. 4,350,842; 4,298,415; French Pat. No. 1,242,540; and German Auslegeschrift No. 1,165,122; each of which possesses inherent limitations relating to convenience of manufacture, convenience of use, or both.